a) Field of the Invention
The invention relates to an extracorporeal therapy apparatus for treating concretions and tissue by means of sound waves in the body of a patient, having a generator device for producing the sound waves, having a spot film device and using an available X-ray device for locating an object for therapy.
b) Description of the Prior Art
European patent application no. 0 402,584 describes a therapy apparatus of the type mentioned above in the form of a lithotripter. A spot film device consisting of a substrate of X-ray negative material and several spot film markers of X-ray positive material embedded therein, is mounted externally and directly on the head of a shock wave generator. Four spot film markers or reference points are provided, and in each case two spot film markers on the substrate each define one spot film line, so that two intended spot film lines are defined. This shock wave generator thus equipped is used in conjunction with an available X-ray device of C-arm construction. The two spot film lines intersect at a point which has to be brought into line with the focal point of the shock wave generator and where the object for therapy in the patient is adjusted later.
Although this spot film device makes for easier adjustment of the X-ray device onto the focus of the shock wave generator and hence onto a concretion in the body of a patient, carrying out adjustment and hence location using this spot film device is nevertheless still awkward and unsafe. After coarse adjustment of the available X-ray device onto the spot film device, initially the bundle of rays from the X-ray device must be aligned with the first spot film line of the spot film device. Then a hypothetical focal point on the shock wave generator must be fixed on a first line corresponding to the first spot film line on the screen of a monitor and then the object for therapy in the patient also visible on the screen must be adjusted onto the hypothetical focus. Several X-ray images are taken to obtain this result. The third spatial coordinate of the therapy point in the patient with respect to the hypothetical focus can be seen by pivoting the X-ray device into the second spot film line of the spot film device. By conventional adjustment of the operating table, on which the patient is situated, the object for therapy in the patient is then adjusted into the final hypothetical focal point; this means that the true focus of the shock wave generator is then in fact aligned with the object for therapy. Several X-ray images are also taken for this result. Overall the X-ray load is thus relatively high. Furthermore, the spot film device is unprotected and may itself be easily displaced, for example by bumping.
German Offenlegungsschrift 4,007,669 describes a lithotripter, the shock wave generator of which is provided with an X-ray device, the ray axis of which coincides with the focus of the generator and which consists of an X-ray cone and the actual X-ray source. German Offenlegungsschrift 3,916,093 describes a further lithotripter which is also rigidly connected to an X-ray device of C-arm support construction which can be adjusted in three spatial coordinates. These lithotripters have a special C-arm for the X-ray device which is always rigidly connected to the shock wave generator.
The object of the invention consists in improving an extracorporeal therapy apparatus of the type mentioned in the introduction so that it is possible to position an available X-ray device with respect to the therapy apparatus for the purpose of more rapid X-ray location of the patient's object for performing the therapy quickly, safely and simply.